Korg Poly61M - Syncing the arpegiator to MIDI Time Clock

This the very early stage of my new project : to sync the arpeggiator with MIDI Time Clock.

Update: this project is still (slowly) evolving.
The MIDI board (KLM605) is based on a 63B03 (IC4), where a 2764 (IC2) contains the program (8K EPROM).
My first idea was to get the MIDI flow after the PC900. But now, I wonder if I can decompile the 2764...